Light emission from color centers in phosphorus-doped diamond
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2022-01-01 |
| Journal | EPJ Web of Conferences |
| Authors | Florian Sledz, Assegid M. Flatae, S. Lagomarsino, Savino Piccolomo, Shannon S. Nicley |
| Institutions | Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, Fondazione Bruno Kessler |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis research focuses on creating electrically excitable single-photon emitters (SPEs) by integrating Silicon-Vacancy (SiV) color centers into n-type (Phosphorus-doped) diamond films grown via Chemical Vapor Deposition (CVD).
- Core Achievement: Successful creation and characterization of single SiV centers in P-doped n-type diamond, demonstrating stable single-photon emission characteristics.
- Device Strategy: Transitioning from complex, poorly reproducible p-i-n diode structures to simplified Schottky diodes, requiring only an n-type diamond layer and metal contacts for hole injection.
- Material System: Homo-epitaxial diamond films doped with Phosphorus (P) during MWPECVD growth to achieve n-type semiconducting properties.
- SiV Integration: SiV centers were introduced via shallow Si-ion implantation (depth ≤ 200 nm) followed by high-temperature vacuum annealing (1200 °C).
- Thermal Performance: SiV centers remain photostable up to 100 °C, suggesting suitability for high-temperature operation, which is critical given the high activation energy (~0.6 eV) of P donors.
- Future Outlook: The system is promising for robust, wide-temperature-range light-emitting devices (LEDs) and electroluminescent single-photon sources.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| CVD Reactor Frequency | 2.45 | GHz | MWPECVD growth |
| Methane Concentration (Sample A) | 0.09 | % | In H2 plasma |
| Methane Concentration (Samples B/C) | 0.15 | % | In H2 plasma |
| PH3/CH4 Ratio (Sample A) | 4300 | ppm | P-doping concentration |
| PH3/CH4 Ratio (Sample C) | 5000 | ppm | Constant P-doping |
| Gas Purity (H2, CH4) | <1 | ppb | 9 N purity |
| Si-Ion Implantation Depth | ≤ 200 | nm | Shallow implantation |
| Si-Ion Implantation Fluences | 107 to 1014 | cm-2 | Range investigated |
| SiV Activation Temperature | 1200 | °C | High-vacuum annealing |
| Annealing Vacuum Pressure | ~10-7 | mbar | High-vacuum conditions |
| P Donor Activation Energy | ~0.6 | eV | Requires high temperature for efficient electrical operation |
| SiV Photostability Limit | 100 | °C | Tested temperature limit in ambient conditions |
| Excitation Wavelength (PL) | 532 or 690 | nm | CW laser excitation |
Key Methodologies
Section titled âKey MethodologiesâThe fabrication process involves three primary steps: n-type diamond growth, SiV center creation via implantation, and thermal activation.
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N-Type Diamond Growth (MWPECVD):
- Reactor: Utilized both in-house built 2.45 GHz reactors and ASTEX PDS17 reactors.
- Doping: Phosphorus (P) was introduced using Phosphine (PH3) diluted in H2 (200 ppm source).
- Gas Control: High-purity H2 and CH4 (filtered to <1 ppb) were used to minimize nitrogen contamination, which causes competing NV center fluorescence.
- Doping Profiles: Both constant P-doping (Sample C: 5000 ppm PH3/CH4) and gradient P-doping (Sample B: 0 to 20,000 ppm PH3/CH4) were explored.
-
Si-Ion Implantation:
- Equipment: 3 MV Tandetron accelerator equipped with a Negative Sputter Ion Source.
- Energy Control: Aluminum (Al) metal foils were used to reduce the ion energy down to a few tens of keV, ensuring shallow implantation.
- Depth: Implantation was targeted to be shallow, resulting in an expected depth of ≤ 200 nm from the surface.
- Fluence Range: Five different fluences were tested, ranging from 107 cm-2 (for single-photon observation) up to 1014 cm-2.
-
Thermal Activation:
- Annealing: Samples were placed in a custom-designed furnace.
- Conditions: Annealing was performed at 1200 °C under high-vacuum conditions (~10-7 mbar).
- Purpose: This step enables the activation and lattice incorporation of the SiV color centers in the P-doped samples.
Commercial Applications
Section titled âCommercial ApplicationsâThis technology, focusing on robust, electrically driven diamond color centers, is highly relevant for next-generation optoelectronics and quantum technologies.
- Quantum Photonics:
- Electroluminescent Single-Photon Sources (SPEs) operating at room temperature, essential for quantum cryptography and linear optical quantum computing.
- Integrated quantum circuits where electrical excitation simplifies device architecture and improves energy efficiency.
- High-Temperature Electronics/Optoelectronics:
- Diamond-based Light-Emitting Diodes (LEDs) that maintain or improve performance at high operating temperatures (100 °C and above), unlike conventional semiconductor LEDs which degrade.
- Devices suitable for harsh environments or high-power applications where thermal management is challenging.
- Advanced Sensing:
- Development of compact, electrically pumped SiV-based sensors (e.g., temperature or strain sensors) utilizing the stable optical properties of the color centers.
- Diamond Material Science:
- Providing a robust platform for studying charge transport and defect engineering in n-type diamond, crucial for developing diamond-based transistors and power devices.
View Original Abstract
Light emission from color centers in diamond is being extensively investigated for developing, among other quantum devices, single-photon sources operating at room temperature. By doping diamond with phosphorus, one obtains an n-type semiconductor, which can be exploited for the electrical excitation of color centers. Here, we discuss the optical properties of color centers in phosphorus-doped diamond, especially the silicon-vacancy center, presenting the single-photon emission characteristics and the temperature dependence aiming for electroluminescent single-photon emitting devices.